Skin tone evenness and/or the appearance of hyperpigmentary spots, such as solar lentigines (age spots), are common concerns among beauty conscious consumers. As such, cosmetic compositions and methods for addressing these consumer concerns are continuing areas of high interest. In melanocytes, the ubiquitin-proteasome system is known to regulate skin pigmentation by degrading tyrosinase or microphthalmia-associated transcription factor. Further, it is believed that up-regulation of proteasomal protease activity may lead to reduced melanin production in melanocytes. See, e.g., Hakozaki et al., A regulator of ubiquitin-proteasome activity, 2-hexyldecanol, suppresses melanin synthesis and the appearance of facial hyperpigmented spots, British Journal of Dermatology 2013, 169 (Supp 2), pp 39-44. See, also, Watabe et al., Regulation of tyrosinase processing and trafficking by organellar pH and by proteasome activity, J Biol Chem 2004, 279, pp 7971-81 and Ando et al., Role of the ubiquitin-proteasome system in regulating skin pigmentation, Int J Mol Sci 2009, 10, pp 4428-34. Improved cosmetic compositions and methods that may up-regulate proteasomal protease activity are believed to be desirable.